How can i get the sum of interior angles

How can i get the sum of interior angles of any polygon ?

The sum of interior angles of a 3 Point polygon = 1 ( triangle )  =   $$1*\pi$$

The sum of interior angles of a 4 Point polygon = 2 ( triangle )  =   $$2*\pi$$

The sum of interior angles of a 5 Point polygon = 3 ( triangle )  =   $$3*\pi$$

The sum of interior angles of a 6 Point polygon = 4 ( triangle )  =   $$4*\pi$$

$$\dots$$

The sum of interior angles of a n Point polygon = n-2 ( triangle )  =   $$\qquad\small{\text{$ (n-2)*\pi \quad $ or $ \quad (n-2)* 180 \ensurement{^{\circ}} $
}}$$

different polygons have different sums....which one do you want?

All you have to do is change the caculator to the angle version that's on the bottom left corner.